Film adhesive and process for production thereof

ABSTRACT

The present invention provides a film adhesive comprising, as the main constituent, a polyimide resin having a glass transition temperature of 350° C. or lower and soluble in organic solvents, which polyimide resin is obtained by reacting at least one of the following acid components (A) and (B) 
     (A) 4,4&#39;-oxydiphthalic acid dianhydride 
     (B) 3,3&#39;,4,4&#39;-biphenyltetracarboxylic acid dianhydride and/or 3,3&#39;,4,4&#39;-benzophenonetetracarboxylic acid dianhydride 
     with at least one of the following amine components (C) and (D) 
     (C) a siloxane compound represented by the following general formula (1) and/or 2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR1##  wherein R 1  and R 2  are each a bivalent aliphatic (C 1-4 ) or aromatic group; R 3 , R 4 , R 5  and R 6  are each a mono-valent aliphatic or aromatic group; and k is an integer of 1-20, 
     (D) bis(aminophenoxy)benzene and/or dimethylphenylene-diamine 
     to give rise to ring closure of imide, as well as a process for producing said film adhesive.

TECHNICAL FIELD

The present invention relates to a polyimide film adhesive which hasexcellent heat resistance and low water absorption, which is suitablefor use in electronics applications particularly as a material formounting of semiconductors, which has excellent adhesion to siliconsubstrates and metals and which can be applied at low temperatures in ashort period of time.

BACKGROUND ART

In recent years, while semiconductor chips have come to possess a higherfunction and a larger capacity and accordingly have become larger insize, the packages containing semiconductor chips are required to havean external form same as or even smaller than the conventional form soas to meet the demand for smaller electronic devices. In response tothis trend, some new mounting methods allowing the high-density mountingof high-density semiconductor chips have been proposed. One is a LOC(lead-on-chip) structure proposed for memory devices, wherein a diepad-free lead frame and chips are fixed to each other with adouble-coated adhesive tape. Meanwhile, in logic devices, amulti-layered lead frame structure has been proposed in which theelectric source and the glands are provided in different frames and themetal plates for heat radiation are provided in a plurality of layers.While in the conventional methods, the chip area was too large to securethe area for inner leads, in the above new methods, semiconductor chipsand a lead frame are bonded with a double-coated adhesive tape and canbe accommodated in a package having the same external form as theconventional package although the chip area is larger due to the largercapacity of chips. In the new methods, it is possible to rationalizein-chip wiring and wire bonding, shorten the length of wire for quickersignal, radiate the heat generated by the higher consumption of electricpower, and make smaller the size of a device.

In the devices employing the above new mounting methods, there existvarious adhesion interfaces between same materials or between differentmaterials, such as chip vs. lead frame, lead frame vs. plate, lead framevs. lead frame and the like. Therefore, the reliability of a device isgreatly influenced by the adhesion reliabilities of said interfaces. Theadhesion reliabilities must withstand the temperatures employed duringthe assembling of a device and further must be sufficient when thedevice is under humidity or under humidity and heat. Further, adhesionworkability is also an important item. In semiconductor apparatuses ofCOL or LOC structure, the semiconductor chips and the lead frame arefixed to each other with an adhesive. This adhesive is required to havean excellent adhesivity so that the adhesion interfaces do not causepeeling under humidity or under thermal stresses caused by reflowsoldering, temperature cycle, etc. The presence of a large amount ofvolatile components in the adhesive is not preferable because, when itis applied with heating, the volatile components contaminate the workingenvironment, leads, etc. Desirably, the adhesive can complete adhesionin a period of time as short as possible, in view of the massproductivity of a device.

As such an adhesive, there have heretofore been used paste-likeadhesives and adhesives obtained by coating an adhesive on aheat-resistant base. As the adhesive, there are used thermosettingresins of epoxy resin type, acrylic resin type or rubber-phenolic resintype; however, they do not satisfy the requirements for a highlyreliable adhesive, because they contain a large amount of ionicimpurities, require a high temperature and a long time for thermosettingand are not productive, generate a large amount of volatile mattersduring thermosetting and contaminate leads, and are highly hygroscopic.Thus, no satisfactory adhesive has not yet been found.

Meanwhile, with respect to the heat-resistant film adhesive which iscontact-bondable with heating, some film adhesives are known. Forexample, hot-melt adhesives of polyamideimide type or polyamide type aredescribed in Japanese Patent Application Kokai (Laid-Open) No.282283/1989; a process for producing a flexible printed circuit boardusing a polyimide type adhesive is described in Japanese PatentApplication Kokai (Laid-Open) No. 157190/1983; and thermosettingpolyimide type film adhesives are described in Japanese PatentApplication Kokai (Laid-Open) Nos. 235382/1987, 235383/1987 and15663/1990. However, the polyamide type or polyamide-imide type resinshave a drawback of high water absorption owing to the hydrophilicity ofthe amide group, and have had a limitation in using them as an adhesivefor electronics applications wherein reliability is required. Thethermosetting polyimide type film adhesives require the conditions forcontact bonding with heating, of 275° C., 50 kgf/cm² and 30 minutes, ormust be cured from a semi-cured state at a high temperature for a longtime, or generate condensation water during curing; therefore, they havebeen insufficient as an film adhesive for use in electronic parts whichare sensitive to heat, pressure, water, etc. or in applications whereinmass productivity is required.

For the reasons mentioned above, it is desired to develop an adhesivesuitable for the new mounting methods, particularly an adhesive tapefrom productivity standpoint.

Meanwhile, polyimide resins have high heat resistance, flame retardancyand excellent electrical insulating property and, accordingly, are inwide use in electric and electronic applications. However, conventionalpolyimide resins have high hygroscopicity and have no sufficientprocessability since they are insoluble and non-fusible or have veryhigh melting points though they have excellent heat resistance. They areused as a material for mounting of semiconductors, in an insulating filmbetween layers, a surface protective film, etc. In using them, apolyamic acid (a polyimide resin precursor) soluble in an organicsolvent is coated on a semiconductor surface and the coatedsemiconductor is heated to remove the solvent and allow the imidizationof the precursor to proceed. At that time, the acid amide type solventused has a high boiling point and causes foaming of the resultant film;and a high-temperature (250° C. or higher) drying step is necessary toevaporate the solvent completely and the device is inevitably exposed toa high temperature. These matters incur reduction in yield in theassembling step. Moreover, the conventional polyimide resins have highhygroscopicity and have caused, in some cases, a problem that the waterabsorbed by them is vaporized all at once at high temperatures to causebulging or cracking.

The present inventors made extensive study in order to obtain apolyimide film adhesive which can be applied at low temperatures in ashort time, which has excellent heat resistance and which has low waterabsorption. As a result, the present inventors have found that apolyimide resin of particular structure achieves the above task, andhave completed the present invention.

DISCLOSURE OF THE INVENTION

The present invention resides in a film adhesive comprising, as the mainconstituent, a polyimide resin having a glass transition temperature of350° C. or lower and soluble in organic solvents, which polyimide resinis obtained by reacting at least one of the following acid components(A) and (B)

(A) 4,4'-oxydiphthalic acid dianhydride

(B) 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and/or3,3',4,4'-benzophenonetetracarboxylic acid dianhydride

with at least one of the following amine components (C) and (D)

(C) a siloxane compound represented by the following general formula (1)and/or 2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR2## wherein R₁ andR₂ are each a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅and R₆ are each a mono-valent aliphatic or aromatic group; and k is aninteger of 1-20,

(D) bis(aminophenoxy)benzene and/or dimethylphenylene-diamine

to give rise to ring closure of imide.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is capped, at the molecular ends,with an acid anhydride represented by the following general formula (2)or an aromatic amine represented by the following general formula (3):##STR3## (X is at least one group selected from ##STR4## wherein Y is atleast one group selected from hydrogen atom and methyl, ethyl, propyl,butyl, phenyl, methoxy, ethoxy, propoxy, butoxy and phenoxy groups.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the acidcomponent (A), 4,4'-oxydiphthalic acid dianhydride in an amount of 60mole % or more based on the total amount of the acid components.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the acidcomponent (B), p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride in proportions satisfying 0.5≦p/(p+q)≦0.9.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the aminecomponent (C), a siloxane compound represented by general formula (1) inan amount of 5-60 mole % based on the total amount of the aminecomponents.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the aminecomponent (D), 1,3-bis(3-aminophenoxy)benzene in an amount of 10-90 mole% based on the total amount of the amine components.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)-polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine in proportions satisfying a/(a+b)≧0.6,0.6>b/(a+b)≧0, 0.1≦c/(c+d+e)≦0.6, 0.6≦(c+d)/(c+d+e), 0≦e/(c+d+e)<0.6 and0.950<(a+b)/(c+d+e)<1.02.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed of, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine, and wherein the polyimide resin iscapped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of a,b, c, d, e, f and g satisfy 0.6≦a/(a+b+0.5f), 0≦b/(a+b+0.5f)<0.6,0.1≦c/(c+d+e+0.5g)≦0.6, 0≦e/(c+d+e+0.5g)<0.6, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+d+e+0.5g)≦0.05 and either of f and g is 0.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene in proportions satisfying 0.5≦p/(p+q)≦0.9and 0.1≦d/(c'+d)≦0.9.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene, and wherein the polyimide resin iscapped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of p,q, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9, 0.1≦d/(c'+d+0.5g)≦0.9,0.01≦f/(p+q+0.5f)≦0.05 and 0.01≦g/(c'+d+0.5g)≦0.05 and either of f and gis 0.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed by using, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of p, q, c, c' and d satisfy 0.5≦p/(p+q)≦0.9,0.1≦q/(p+q)≦0.5 and 0.05≦c/(c+c'+d)≦0.5.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, f moles ofan acid anhydride represented by general formula (2) or g moles of anaromatic amine represented by general formula (3), and wherein the molarratios of p, q, c, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9,0.1≦q/(p+q+0.5f)≦0.5, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(p+q+0.5f)≦0.05and 0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is 0.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed of, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof one or two tetracarboxylic acid dianhydrides selected from the groupconsisting of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of a, b c, c' and d satisfy a/(a+b)≧0.6, b/(a+b)≦0.4and 0.05≦c/(c+c'+d)≦0.5.

The present invention resides also in a film adhesive according to theabove, wherein the polyimide resin is composed of, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof one or two tetracarboxylic acid dianhydrides selected from the groupconsisting of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of a, b, c, c', d, f and g satisfy a/(a+b+0.5f)≧0.6,b/(a+b+0.5f)≦0.4, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is 0.

The present invention resides also in a film adhesive comprising aheat-resistant film base and the above polyimide resin applied on oneside or both sides of the film base.

The present invention resides also in a film adhesive according to theabove, wherein the heat-resistant film base is a polyimide film having aglass transition temperature of 350° C. or higher.

The present invention resides also in a process for producing a filmadhesive, which comprises casting, on one side or both sides of asubstrate, an organic solvent solution of the above polyimide resin.

The present invention resides also in a process for producing a filmadhesive according to the above, wherein the substrate is a polyimidefilm having a glass transition temperature of 350° C. or higher.

The present invention resides also in a process for producing a filmadhesive according to the above, which comprises casting an organicsolvent solution of the polyimide resin on one side or both sides of asubstrate, drying the cast solution and then peeling the substrate.

The present invention resides also in a process according to the above,wherein the substrate is a biaxially stretched polyester film.

The present invention resides also in a process for producing a filmadhesive according to the above, which comprises casting the polyimideresin solution on a substrate by use of an organic solvent having aboiling point of 180° C. or lower, drying the cast polyimide resinsolution and peeling the dried polyimide resin from the substrate.

DETAILED DESCRIPTION OF THE INVENTION

4,4'-Oxydiphthalic acid dianhydride used in obtaining the polyimideresin of the present invention is represented by formula (4);3,3',4,4'-biphenyltetracarboxylic acid dianhydride is represented byformula (5); 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride isrepresented by formula (6); 2,2-bis(4-(4-aminophenoxy)phenyl)propane isrepresented by formula (7); 1,3-bis(3-aminophenoxy)benzene, which is atypical example of bis(aminophenoxy)benzene, is represented by formula(8); 2,5-dimethyl-p-phenylenediamine, which is a typical example ofdimethylphenylenediamine, is represented by formula (9); andα,ω-bis(3-aminopropyl)polydimethylsiloxane, which is a typical exampleof the siloxane compound of formula (1), is represented by formula (10).In formula (10), k is preferably in the range of 4-10 in view of theglass transition temperature, adhesion and heat resistance of thepolyimide resin. These siloxane compounds can be used not only singlybut also in combination of two or more. Use of, in particular, a blendof a siloxane compound of k=1 and a siloxane compound of k=4-10 ispreferable for applications wherein adhesivity is very important.##STR5##

Bis(aminophenoxy)benzene is preferably 1,4-bis(3-aminophenoxy)benzene,1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene or thelike. Dimethylphenylenediamine is preferably2,5-dimethyl-p-phenylenediamine or 2,4-dimethyl-m-phenylenediamine.

It is important that the amount ratios of individual components be inthe above-mentioned ranges. The molar proportion of 4,4'-oxydiphthalicacid dianhydride, which is an important constituent of the acidcomponents, or the siloxane compound is very important for thesolubility of the polyimide resin obtained and, when said molarproportion is not in the above range, a feature of the present inventionof being soluble in low-boiling solvents is lost. In formula (1), k ispreferably 1-10, more preferably 4-10, and mixed use of a monomer ofk=4-10 and a monomer of k=1 is particularly preferable. The amount ofthe α,ω-bisaminosiloxane compound represented by formula (1) ispreferably 5-60% based on the total amine components. An amount of 5% orless is not preferable because the polyimide resin obtained has lowersolubility in organic solvents, higher water absorption and lowerwettability on an adhered to be applied, which makes adhesion in a shorttime difficult. An amount more than 60% is not preferable because thepolyimide resin obtained has a very low glass transition temperature andhas inferior properties at high temperatures, which incurs insufficientheat resistance.

The molar proportion of 2,2-bis(4-(4-aminophenoxy)phenyl)propane ispreferably in the range of 10-90 mole % based on the total aminecomponents. When the proportion is outside the range, problems arise insolubility and heat resistance.

Addition of dimethylphenylenediamine can increase the heat resistance ofthe polyimide resin obtained, without reducing its solubility inlow-boiling solvents. Further, 1,3-bis(3-aminophenoxy)benzene can beadded when the polyimide resin obtained is required to havelow-temperature adhesion in adhesive applications.

In the present invention, the tetracarboxylic acid dianhydrides as theacid components further include, besides those mentioned above, forexample, 1,2,4,5-benzenetetracarboxylic acid dianhydride (PMDA),2,2'-bis(4-(3,4-dicarboxyphenyl)phenyl)propane and3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride. One or moreof these can be used together with the above-mentioned tetracarboxylicacid dianhydrides. Further, a dicarboxylic acid anhydride such asphthalic anhydride or the like can be added as a molecular weightmodifier.

The tetracarboxylic acid dianhydride as an essential component is usedin an amount of 50 mole % or more, preferably 70 mole % or more based onthe total acid components. An amount of less than 50 mole % is notpreferable because the polyimide resin obtained has a high glasstransition temperature, which requires a very high temperature duringadhesion, or has inferior adhesivity.

Similarly, the diamines include, besides the above-mentioned essentialdiamines, diamines such as 4,4'-diaminodiphenyl ether (4,4'-DDE),3,3'-diaminodiphenyl ether (3,3'-DDE), 3,4'-diaminodiphenyl ether(3,4'-DDE), 4,4'-diaminodiphenyl sulfone (4,4'-DDS),3,3'-diaminodiphenylsulfone (3,3'-DDS),2,2-bis-4-aminophenylhexafluoropropane (BAPF),2,2-bis-4-aminophenoxyphenylhexafluoropropane (BAPPF),bis-4-(4-aminophenoxy)phenylsulfone (BAPS),bis-4-(3-aminophenoxy)phenylsulfone (BAPSM), 4,4'-diaminobenzanilide(DABAN), m-phenylenediamine, p-phenylenediamine,4,4'-diaminodiphenylmethane (DDM), 2,4-diaminotoluene and the like. Oneor more of these can be used together with the essential diamines. Thediamine compound as an essential component is used in an amount of 50mole % or more, preferably 70 mole % or more based on the total diaminecomponents. Similarly to the case of the acid components, an amount of50 mole % or less is not preferable because various drawbacks arebrought about, for example, the polyimide resin obtained has a highglass transition temperature, which requires a very high temperatureduring adhesion, or has inferior adhesivity.

The polyimide resin, by being capped at the molecular ends to controlthe molecular weight, can have a melt viscosity suitable for adhesion toan adhered and can have higher wettability for higher adhesivity. Theamount of the end-capping agent, i.e. the acid anhydride or the aromaticamine is desirably in the range of 1-5 mole %. An amount less than 1mole % is not preferable because the resulting polyimide resin has toolarge a molecular weight and is insoluble in low-boiling solvents insome cases, and has inferior wettability caused by the increase in meltviscosity, in applications where adhesivity is very important. When saidamount is more than 5 mole %, the polyimide resin has a significantlyreduced molecular weight and has a problem in heat resistance.

As the end-capping agent, there can be cited an acid anhydriderepresented by general formula (2) and an aromatic amine represented bygeneral formula (3).

As the acid anhydride, there are used phthalic anhydride, maleicanhydride, nadic anhydride, etc. and, as the aromatic amine, there areused p-methylaniline, p-methoxyaniline, p-phenoxyaniline, etc.

In the polycondensation reaction, the molar ratio of the tetracarboxylicacid dianhydride components and the diamine components is an importantfactor which determines the molecular weight of the polyamic acidobtained. It is well known that there is a correlation between themolecular weight of a polymer and its properties, particularly betweenthe number-average molecular weight and the mechanical properties. Alarger number-average molecular weight gives superior mechanicalproperties. Accordingly, a polymer is required to have an appropriatelyhigh molecular weight in order for the polymer to show an excellentstrength when put into practical use as an adhesive. In the presentinvention, the equivalent ratio r of the acid anhydride components tothe amine components is in the range of preferably 0.950≦r≦1.06, morepreferably 0.975≦r≦1.06, wherein r=(equivalent number of total acidcomponents)/(equivalent number of total amine components). When r issmaller than 0.950, the polyimide resin obtained has a small molecularweight, is fragile and therefore has low adhesivity. An r larger than1.06 is not preferable because, in some cases, the unreacted carboxylicacids give rise to decarboxylation during heating and cause gasgeneration and foaming.

The reaction of the acid anhydrides and the amines is conducted in anaprotic polar solvent by a known method. The aprotic polar solvent isexemplified by N,N-dimethylformamide (DMF), N,N-dimethylacetamide(DMAC), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diglyme,cyclohexanone and 1,4-dioxane. The aprotic polar solvent may be usedsingly or as a mixture of two or more. At that time, a non-polar solventcompatible with the aprotic polar solvent may be used together with theaprotic polar solvent. An aromatic hydrocarbon such as toluene, xylene,solvent naphtha or the like is often used. The proportion of thenon-polar solvent in the mixed solvent is preferably 30% by weight orless. The reason is that when the proportion of the non-polar solvent is30% by weight or more, the mixed solvent has low solvency and mayprecipitate the polyamic acid formed. In the reaction of thetetracarboxylic acid dianhydrides with the diamines, sufficiently drieddiamine components are dissolved in the above-mentioned reaction solventwhich is dehydrated and purified; thereto are added sufficiently driedtetracarboxylic acid dianhydrides having a ring closure ratio of 98%,preferably 99% or higher to allow the reaction to proceed.

The thus-obtained polyamic acid solution is then heated in an organicsolvent to give rise to dehydration, cyclization and resultantlyimidization for formation of a polyimide. The water generated by theimidization reaction hinders the ring-closing reaction; therefore, anorganic solvent non-compatible with water is added to the system andazeotropic distillation is conducted using an apparatus such asDean-Stark tube or the like, to discharge the water out of the system.Dichlorobenzene is known as the organic solvent non-compatible withwater, but it may invite the presence of chlorine in the polyimide resinobtained. Hence, when the polyimide resin obtained is used inelectronics applications, the above-mentioned aromatic hydrocarbon isused preferably. Further, it is possible to use, as a catalyst forimidization reaction, a compound such as acetic anhydride, β-picoline,pyridine or the like.

In the present invention, the degree of ring closure of imide is desiredto be as high as possible. A low imidization degree is not preferablebecause, during adhesion, the heat generated gives rise to furtherimidization and consequently generates water. Desirably, an imidizationdegree of 95% or more, preferably 98% or more is achieved during theimidization.

In the imidization, if strong heating is conducted from the start beforea polyimide film is formed, there is formed a rough surface or apartially stretched surface; therefore, it is preferable that heating bestarted at a low temperature and the temperature be increased slowly.For example, heating is conducted continuously from 100° C. to 350° C.in 0.5 hour or more. When the heating time is less than 0.5 hour,solvent removal becomes insufficient and ring closure of imide becomesinsufficient and resultantly the polyimide resin obtained has nosufficient properties, although these matters vary depending upon thefilm thickness of the polyimide resin obtained. Alternatively, thetemperature elevation may be conducted stepwise by conducting heating,for example, at 100° C. for 30 minutes, then at 150° C. for 30 minutes,at 200° C. for 30 minutes, at 250° C. for 30 minutes, at 300° C. for 30minutes and at 350° C. for 30 minutes.

In the present invention, the thus-obtained polyimide solution is notcoated on a substrate as it but is added to a poor solvent toreprecipitate the polyimide resin for removal of unreacted monomers andpurification. The polyimide resin after purification, filtration anddrying is redissolved in an organic solvent to prepare a varnish. As thesolvent, there is selected a solvent having a boiling point of 180° C.or below in order to minimize the residual solvent in the film to beprepared and also in view of the economy and workability of the coatingand drying steps of the varnish. In the present invention, there can beused, as ketone type solvents, acetone (b.p.: 56.5° C.), methyl ethylketone (b.p.: 79.6° C.), methyl isobutyl ketone (b.p.: 118° C.),cyclopentanone (b.p.: 130.6° C.) and cyclohexanone (b.p.: 155.6° C.)and, as ether type solvents, 1,4-dioxane (b.p.: 101.1° C.),tetrahydrofuran (b.p.: 66° C.) and diglyme (b.p.: 162° C.). Thesesolvents may be used singly or in admixture of two or more.N,N-dimethylformamide and N,N-dimethylacetamide, both of which are amidetype solvents, have boiling points of 180° C. or below, respectively.They, however, are not preferable because they have high interactionwith the polyimide resin and gives a low evaporation rate andaccordingly, unless drying is conducted at 200° C. or above, it isdifficult to remove the solvent molecules which are in solvation withthe polyimide resin, and the solvent remains in the polyimide film in alarge amount. Said solvents are not preferable, either, because they arehighly hygroscopic and, when the polyimide varnish containing them ismade into a film by coating, the film tends to absorb water and causewhitening. In the present invention, the residual solvent content in thefilm can be controlled at a low level, as compared with those inconventional polyimide films obtained by heating a polyamic aciddissolved in a high-boiling polar solvent (e.g. NMP) at the time of filmformation to give rise to imidization, and further the contamination ofan adhered by the thermal decomposition products of the polyimide resincan be prevented.

To the polyimide resin varnish can be added, if necessary, variousadditives for imparting surface smoothness, such as smoothing agent,levelling agent, defoamer, adhesion improver and the like. An aromatichydrocarbon type solvent can also be added in such an amount that it isuniformly soluble, in order to control the evaporation rate of thesolvent in the polyimide resin varnish.

In order to use the polyimide resin varnish as a film adhesive, thepolyimide resin varnish is casted into a film shape and used as a filmof polyimide resin alone or in one piece integrated with a filmsubstrate.

In casting the polyimide resin varnish, there can be used, for example,an apparatus in which a coating device (e.g. flow coater or roll coater)and a hot-air drying chamber are combined. The polyimide resin varnishis coated on a substrate, and the coated substrate is introduced into ahot-air drying chamber and dried at a temperature and an air volumesufficient to evaporate the solvent in the varnish. As the substrate,there can be used thin metal plates of stainless steel, aluminum,copper, etc. as well as plastic films such as polyimide film, biaxiallystretched polyester film and the like. Of them, a polyimide resin filmis most preferable because it has a small thermal expansion coefficient,excellent dimensional stability to temperature change, high flexibility,easy handleability, high adhesion to the adhesive resin of the presentinvention, etc. In particular, a film made of a polyimide resin having astructure represented by formula (11) or (12) is preferable. ##STR6##

When the polyimide resin is used as a film adhesive by itself, thepolyimide resin film formed on a substrate is peeled off from thesubstrate and used. When the polyimide resin is used as one-pieceadhesive integrated with a substrate, the polyimide resin film formed onone or both sides of a substrate is used as such.

The present invention can also be used as an adhesive of two-layer orthree-layer structure when the above substrate itself is used as a base.In that case, a polyimide film can be used advantageously as thesubstrate. However, in order for the adhesive of the present inventionto sufficiently exhibit the characteristics of low water absorption andlow ionic impurities content, the present adhesive preferably comprisesonly the polyimide resin of the present invention and contains neithersubstrate nor base. In a case where the polyimide resin is combined witha solvent having a boiling point of 180° C. or below and a polyesterfilm, no releasing agent (this agent is required when a metal substrateis used) is required and the polyimide resin can be easily peeled offfrom the polyester film. No use of a releasing agent (this agent hindersthe adhesion property of the polyimide resin) is very advantageous inthe production of a film adhesive, is most suited for the object of thepresent invention, and enables the best use of the heat resistance andhigh reliability of the polyimide.

How to use the polyimide adhesive of the present invention is notparticularly restricted. It can be used as a film adhesive which can becontact-bonded with heating. That is, it is cut into a desired shape andcontact-bonded with heating, using a heated heat block.

The film adhesive of the present invention is characterized by using, asa main constituent, a completely imidized polyimide resin of particularstructure soluble in low-boiling organic solvents. The polyimide resinas an adhesive can have a very low ionic-impurities level by beingreprecipitated and purified, generates substantially no gas when heatedbecause the imidization is conducted using a low-boiling solvent, haslow water absorption and excellent heat resistance, and can be appliedin a very short time as compared with thermosetting adhesives which giverise to a chemical reaction. The present invention, by being processedinto a tape shape, can have excellent adhesion workability and excellentdimensional precision to bonded portions.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is hereinafter described in more detail by way ofExamples and Comparative Examples. However, the present invention is inno way restricted to these Examples.

Example 1

1,170 g of dehydrated and purified NMP and 130 g of xylene were placedin a four-necked flask equipped with an inlet tube for dried nitrogengas, a cooler with a calcium chloride drying tube, a thermometer and astirrer, and were vigorously stirred for 10 minutes with nitrogen gasbeing passed therethrough. Then, thereto were added 73.08 g (0.25 mole)of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and 102.63 g (0.25 mole) of1,3-bis(3-aminophenoxy)benzene. The system was heated to 60° C. andstirred until it became uniform. After the system became a uniformsolution, it was cooled to 5° C. in an ice water bath. Thereto wereadded, in 15 minutes, 101.43 g (0.345 mole) of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and 47.61 g (0.148mole) of 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride both ofpowder form. Thereafter, stirring was continued for 3 hours. During thestirring, the flask was kept at 5° C.

The thus-prepared polyamic acid solution was coated on a polyimide film(UPILEX S manufactured by Ube Industries, Ltd.) having a thickness of 50μm. The coated polyimide film was subjected to a heating treatment in acirculating hot air dryer at 120° C. for 1 hour, at 200° C. for 1 hourand at 300° C. for 1 hour. After cooling, the film was measured forthickness and the thickness of the formed adhesive layer was calculated.The adhesive layer had a thickness of 22 μm. The adhesion surface of thefilm showed no adhesiveness and was tack-free at room temperature.

This adhesive film was cut into a size of 25 mm×50 mm to prepare anadhesive tape. The adhesive tape was bonded to the metal luster surfaceof a 35-μm electrolytic copper foil, using a hot press having a heatblock made of phosphor bronze, whereby a test piece was prepared. Theadhesion conditions were 310° C. and 20 seconds and the pressure appliedonto the adhesion surface was 7 kg/cm² as a result of calculation fromthe gauge pressure and the adhesion area. The test piece had a 180°peeling strength of 1.50 kgf/cm.

Further, the 180° peeling strength after 168-hour treatment in anenvironment of 85° C. and 85% was 1.39 kgf/cm. Thus, the adhesionsurface of the film showed excellent adhesivity to copper. On therupture surface, the adhesive resin layer caused cohesive failure, whichindicated the excellent adhesivity of the adhesive resin layer to thebase (polyimide film). The results are shown in Table 1.

Example 2 and Comparative Examples 1-3

Adhesive tapes were obtained in the same manner as in Example 1 underthe conditions shown in Table 1 and Table 2. The properties of theseadhesive tapes are shown in Table 1 and Table 2.

                  TABLE 1                                                         ______________________________________                                                       Example 1 Example 2                                            ______________________________________                                        Adhesive resin   Figures in                                                                    parentheses                                                                   indicate molar                                                                ratios                                                       Amine components APB     (50)    APB   (50)                                                    BAPP    (50)    BAPP  (50)                                   Acid components  BPDA    (70)    ODPA  (100)                                                   BTDA    (30)                                                 Acid/amine molar ratio                                                                         0.985       0.990                                            Glass transition temperature                                                                   220° C.                                                                            176° C.                                   Thermal decomposition                                                                          533° C.                                                                            562° C.                                   temperature                                                                   Linear expansion coefficient                                                                   5.0 ppm     7.4 ppm                                          Adhesive layer thickness                                                                       22 μm    17 μm                                         Heat-resistant base                                                                            UPILEX S    UPILEX S                                                          50 μm    50 μm                                         Adhesion conditions                                                           Temperature (°C.)                                                                       310         260                                              Time (seconds)   20          10                                               Pressure (kg/cm.sup.2)                                                                         7           6                                                Peeling strength kgf/cm                                                       Ordinary state   1.50        1.66                                             HHBT-168         1.39        1.35                                             Peeling interface                                                                              Cohesive failure                                                                          Cohesive failure                                 ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                                 Comparative                                                                            Comparative Comparative                                              Example 1                                                                              Example 2   Example 3                                       ______________________________________                                        Adhesive resin                                                                           Figures in                                                                    parentheses                                                                   indicate molar                                                                ratios                                                             Amine components                                                                         3,4'-DDE                                                                              (30)   4,4'-DDE                                                                            (100) 3,3'-DDS                                                                            (100)                                        3,3'-DDA                                                                              (70)                                                       Acid components                                                                          BPDA    (70)   PMDA  (100) BPDA  (100)                                        BTDA    (30)                                                       Acid/amine molar                                                                         0.985      0.975       0.985                                       ratio                                                                         Glass transition                                                                         380° C.                                                                           >450° C.                                                                           362° C.                              temperature                                                                   Adhesive layer                                                                           19 μm   20 μm    18 μm                                    thickness                                                                     Heat-resistant base                                                                      UPILEX S   UPILEX S    UPILEX S                                               50 μm   50 μm    50 μm                                    Adhesion conditions                                                           Temperature (°C.)                                                                 310        310         310                                         Time (seconds)                                                                           60         60          60                                          Pressure (kg/cm.sup.2)                                                                   8          8           8                                           Peeling strength                                                                         kgf/cm                                                             Ordinary state                                                                           0.04       <0.01       <0.01                                       HHBT-168   <0.01                                                              Peeling interface                                                                        Peeled from                                                                              Peeled from Peeled from                                            copper surface                                                                           copper surface                                                                            copper surface                              ______________________________________                                    

As shown in Examples 1 and 2, the adhesives each using a polyimide resincomposed of the essential components of the present invention showexcellent adhesivity to copper and also to respective bases (polyimidefilms). Meanwhile, Comparative Examples 1-3 give very inferioradhesivity.

Example 3

989 g of dehydrated and purified NMP was placed in a four-necked flaskequipped with an inlet tube for dried nitrogen gas, a cooler, athermometer and a stirrer, and was vigorously stirred for 10 minuteswith nitrogen gas being passed therethrough. Then, thereto were added58.47 g (0.200 mole) of 1,3-bis(3-aminophenoxy)benzene and 116.00 g(average molecular weight: 870, 0.133 mole) ofα,ω-bis(3-aminopropyl)polydimethylsiloxane. The system was heated to 60°C. and stirred until it became uniform. After the system became auniform solution, it was cooled to 5° C. in an ice water bath. Theretowere added, in 15 minutes, 81.07 g (0.261 mole) of 4,4'-oxydiphthalicacid dianhydride and 19.22 g (0.065 mole) of3,3',4,4'-biphenyltetracarboxylic acid dianhydride both of powder form.Thereafter, stirring was continued for 3 hours. During the stirring, theflask was kept at 5° C.

Then, the nitrogen gas inlet tube and the cooler were removed. ADean-Stark tube filled with xylene was fitted to the flask and 109.9 gof xylene was added to the system. The system was heated to 200° C. inan oil bath and the water generated was removed out of the system. In 4hours of heating, the generation of water from the system was not seen.After cooling, the reaction mixture was placed in a large amount ofmethanol to precipitate a polyimide resin. The solid was collected byfiltration and vacuum-dried at 80° C. for 12 hours to remove thesolvent. The resulting resin was measured for infrared absorptionspectrum by a KBr tablet method, which gave an absorption at 5.6 μm bycyclic imide bond but no absorption at 6.06 μm by amide bond. Thus, itwas confirmed that the resin was 100% imidized. 251.56 g (yield: 91.55%)of the thus-obtained polyimide resin was dissolved incyclohexanone/toluene (90/10 w/w %) to prepare a polyimide resin varnish(resin content: 30%).

This polyimide resin varnish was coated on a polyimide film (UPILEX Smanufactured by Ube Industries, Ltd.) having a thickness of 50 μm. Thecoated polyimide film was heat-dried in a circulating hot air dryer at120° C. for 0.5 hour and at 200° C. for 1 hour. After cooling, the filmwas measured for thickness and the thickness of the formed adhesivelayer was calculated. The adhesive layer had a thickness of 19 μm. Theadhesion surface of the film showed no adhesiveness and was tack-free atroom temperature.

This film adhesive was bonded to the metal luster surface of a 35-μmelectrolytic copper foil, using a hot press having a heat block made ofphosphor bronze, whereby a test piece was prepared. The adhesionconditions were such that contact bonding was conducted at 210° C. for 2seconds and, after pressure release, annealing was conducted at 210° C.for 10 seconds. The pressure applied onto the adhesion surface was 4kg/cm² as a result of calculation from the gauge pressure and theadhesion area. The test piece had a 180° peeling strength of 2.81kgf/cm. Further, the 180° peeling strength after 168-hour treatment inan environment of 85° C. and 85% was 2.66 kgf/cm. Thus, the adhesionsurface of the film showed excellent adhesivity to copper. On therupture surface, the adhesive resin layer caused cohesive failure and nofoaming was seen. It indicated the excellent adhesivity of the adhesiveresin layer to the base (polyimide film). There were also examined theadhesivities to a silicon wafer coated with a polyimide resin (SUMIRESINEXCEL CRC-6061P manufactured by Sumitomo Bakelite Co., Ltd.). They were2.01 kgf/cm and 1.75 kgf/cm, respectively. The results are shown inTable 3, together with other properties.

In the above, the molar ratios of the acids and the amines werea/(a+b)=0.8, c/(c+d+e)=0.4 and (c+d)/(c+d+e)=1, respectively.

Examples 4-7

Polyimide resin varnishes were prepared in the same manner as in Example4 under the conditions shown in Table 3. They were coated on a polyimidefilm to prepare the respective film adhesives. Their properties areshown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________               Example 3                                                                             Example 4                                                                             Example 5                                                                             Example 6                                                                             Example 7                          __________________________________________________________________________    Adhesive resin                                                                           Figures in                                                                    parentheses                                                                   indicate                                                                      molar ratios                                                       Amine components                                                                         APB (60)                                                                              APB (65)                                                                              APB (75)                                                                              APB (60)                                                                              APB (65)                                      APPS                                                                              (40)                                                                              APPS                                                                              (35)                                                                              APPS                                                                              (25)                                                                              APPS                                                                              (25)                                                                              APPS                                                                              (45)                                                              BAPP                                                                              (15)                                   Acid components                                                                          ODPA                                                                              (80)                                                                              ODPA                                                                              (70)                                                                              ODPA                                                                              (100)                                                                             ODPA                                                                              (100)                                                                             ODPA                                                                              (90)                                      BPDA                                                                              (20)                                                                              BTDA                                                                              (30)                PMDA                                                                              (10)                           Acid/amine molar ratio                                                                   0.980   0.985   0.995   0.995   0.985                              Glass transition                                                                         167° C.                                                                        176° C.                                                                        190° C.                                                                        186° C.                                                                        163° C.                     temperature                                                                   Thermal decomposition                                                                    542° C.                                                                        586° C.                                                                        583° C.                                                                        569° C.                                                                        572° C.                     temperature                                                                   Linear expansion                                                                         6.3 ppm 6.1 ppm 3.4 ppm 4.2 ppm 8.3 ppm                            coefficient                                                                   Adhesive layer                                                                           19 μm                                                                              21 μm                                                                              20 μm                                                                              20 μm                                                                              19 μm                           thickness                                                                     Heat-resistant base                                                                      UPILEX S                                                                              UPILEX  UPILEX S                                                                              UPILEX S                                                                              UPILEX S                                      50 μm                                                                              50 μm                                                                              50 μm                                                                              50 μm                                                                              50 μm                           Adhesion conditions                                                           Temperature (°C.)                                                                 210     210     210     210     240                                Time (seconds)                                                                           20      25      10      10      10                                 Pressure (kg/cm.sup.2)                                                                   4       4       4       4       6                                  Peeling strength                                                                         kgf/cm                                                             Ordinary state                                                                           2.81    2.39    1.96    2.09    2.63                               HHBT-168   2.66    2.11    1.72    1.85    2.23                               Peeling interface                                                                        Cohesive                                                                              Cohesive                                                                              Cohesive                                                                              Cohesive                                                                              Cohesive                                      failure failure failure failure failure                            Ionic impurities                                                                         ppm     ppm     ppm     ppm     ppm                                Cl.sup.-   0.633   0.784   0.488   0.531   0.779                              HCOO.sup.- 36.112  31.908  32.437  30.798  35.674                             (COO).sub.2 .sup.-                                                                       0.819   Not detected                                                                          0.977   0.774   0.859                              Na.sup.+   0.479   0.627   0.163   0.382   0.531                              NH.sub.4 .sup.+                                                                          5.350   2.989   4.883   3.192   4.992                              __________________________________________________________________________

Example 8

1,3-Bis(3-aminophenoxy)benzene,2,2-bis(4-(4-aminophenoxy)phenyl)propane,α,ω-bis(3-aminopropyl)polydimethylsiloxane (average molecular weight:870), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and4,4'-oxydiphthalic acid dianhydride were reacted in the same manner asin Example 1 at a molar ratio of 0.4/0.4/0.2/0.3/0.7, to obtain apolyimide resin. This polyimide resin was easily soluble incyclohexanone and could be easily made into a polyimide resin film byusing a polyester film as a substrate. The drying conditions were 120°C.×0.5 hour and then 160° C.×0.5 hour. The film had a glass transitiontemperature of 165° C., and was bonded to a copper foil at 240° C. in 30seconds and showed a peeling strength of 1.77 kgf/cm. The film afteradhesion gave no foaming. Incidentally, the gas generated in the filmwas measured under the same conditions as in Table 4 and was 204 ppm.

Example 9

The polyimide resin solution obtained in Example 8 was coated on apolyimide film (UPILEX S manufactured by Ube Industries, Ltd.) having athickness of 50 μm, and a film adhesive was obtained in the same manner.This film had properties similar to those in Example 8.

Example 10

750 g of dehydrated and purified NMP was placed in a four-necked flaskequipped with an inlet tube for dried nitrogen gas, a cooler, athermometer and a stirrer, and was vigorously stirred for 10 minuteswith nitrogen gas being passed therethrough. Then, thereto were added73.0847 g (0.250 mole) of 1,3-bis(3-aminophenoxy)benzene (APB), 37.8163g (average molecular weight: 840.36, 0.045 mole) ofα,ω-bis(3-aminopropyl)polydimethylsiloxane (APPS) and 1.4971 g 0.006mole, k=1 in formula (10)! of1,3-bis(3-aminopropyl)tetramethyldisiloxane (APPS, k=1). The system washeated to 60° C. and stirred until it became uniform. After the systembecame a uniform solution, it was cooled to 5° C. in an ice water bath.Thereto was added, in 15 minutes, 93.4404 g (0.301 mole) of4,4'-oxydiphthalic acid dianhydride (ODPA) of powder form. Thereafter,stirring was continued for 3 hours. During the stirring, the flask waskept at 5° C.

Then, the nitrogen gas inlet tube and the cooler were removed. ADean-Stark tube filled with xylene was fitted to the flask and 187 g oftoluene was added to the system. The system was heated to 175° C. in anoil bath and the water generated was removed out of the system. In 4hours of heating, the generation of water from the system was not seen.After cooling, the reaction mixture was placed in a large amount ofmethanol to precipitate a polyimide resin. The solid was collected byfiltration and vacuum-dried at 80° C. for 12 hours to remove thesolvent, whereby 186.28 g (yield: 90.5%) of a solid resin was obtained.The resin was measured for infrared absorption spectrum by a KBr tabletmethod, which gave an absorption at 5.6 μm by cyclic imide bond but noabsorption at 6.06 μm by amide bond. Thus, it was confirmed that theresin was nearly 100% imidized. Incidentally, the molar ratios of theacids and the amines were a/(a+b)=1, d/(c+d+e)=0.83 and e/(c+d+e)=0.17,respectively.

The thus-obtained polyimide resin was dissolved in cyclohexanone/toluene(90/10 w/w %) to prepare a polyimide resin varnish having a solidcontent of 25%. This varnish was coated on one side of a polyimide filmUPILEX SGA (trade name) manufactured by Ube Industries, Ltd.! having athickness of 50 μm by use of a reverse roll coater to obtain a filmadhesive in which the adhesive layer had a thickness of 30 μm. Thedrying temperature was 185° C. (maximum temperature) and the drying timewas 6 minutes. This film adhesive was hot-pressed onto a 35 μm copperfoil to prepare a test piece. The film adhesive was contact-bonded onthe treated surface of the copper foil at 250° C. for 2 seconds and,after pressure release, annealing was conducted at 250° C. for 30seconds. The pressure applied on the adhesion surface was 4 kgf/cm² as aresult of calculation from the pressure gauge and the adhesion area. Thetest piece had a 180° peeling strength of 3.43 kgf/cm and showedexcellent adhesivity. On the rupture surface, the adhesive resin causedcohesive failure and no foaming was seen. The results are shown in Table4.

Example 11

The varnish of Example 10 was coated on a biaxially stretched polyesterfilm DIAFOIL (trade name) manufactured by Mitsubishi Rayon Co., Ltd.!having a thickness of 50 μm. The drying temperature was 185° C. (maximumtemperature) and the drying time was 6 minutes. After drying, thepolyester film was removed by peeling to obtain a single-layer film of32 μm in thickness having no substrate. The peeling was easy and had noparticular problem. The results when the film was bonded to the lustersurface of a copper foil in the same manner as in Example 10, are shownin Table 4.

Examples 12-14

Reactions were conducted in the same manner as in Example 10, using therecipes shown in Table 4, to obtain soluble polyimide resins. Filmadhesives were obtained using the polyimide resins. The results ofevaluation for the film adhesives are shown in Table 4. Each of the filmadhesives shows excellent properties.

                                      TABLE 4                                     __________________________________________________________________________                                                       Comparative                                                                         Comparative                          Example                                                                              Example                                                                              Example                                                                              Example                                                                              Example                                                                              Example                                                                             Example              Items           10     11     12     13     14     4     5                    __________________________________________________________________________    Composition                                                                   Acid components                                                               ODPA            100    100    80     100    80           PMDA 100             BTDA                          20                   30                         BPDA                                        20     70                         Amine components                                                              APB             83     83     60     15     45     30    65                   BAPP                                 65     42                                BAPPF                         20                                              APPS (M = 870)  15     15     20     20     10     4,4'-DDE                                                                      70                         APPS (k = 1)    2      2                    3            35                   Acid/amine equivalent ratio r                                                                 1.00   1.00   1.00   1.00   0.99   0.98  0.99                 Varnish solvent Cyclohexanone                                                                        Cyclohexanone                                                                        Dioxane                                                                              Cyclohexanone                                                                        Cyclohexanone                                                                        Insoluble                                                                           Insoluble            Film drying conditions                                                        Maximum temperature                                                                           180    180    170    180    180                               (°C.)                                                                  Time (min)      6      6      6      6      6                                 Constitution                                                                  Base            UPILEX Not used                                                                             UPILEX Not used                                                                             Not used                          Thickness (μm)                                                                             50/30  32     20/50/20                                                                             25     25                                Properties                                                                    Conditions Unit                                                               Water absorption                                                              HH-168 treatment                                                                         %    0.59   0.19   0.56   0.23   0.30                              Generated gas                                                                 GC-MS method                                                                             ppm  95     81     78     101    96                                Generated water                                                               Karl Fischer`s method                                                                    %    0.32   0.16   0.29   0.23   0.20                              Adhesion conditions                                                           Temperature                                                                              °C.                                                                         250    250    250    250    250                               Time       Seconds                                                                            2/30   2/30   2/30   2/30   2/30                              Pressure   kgf/cm.sup.2                                                                       4/0    4/0    4/0    4/0                                      Adherend        Copper Copper Copper Copper Copper                            Peeling strength                                                              180° peeling                                                                      kgf/cm                                                                             3.43   3.32   3.10   3.07   3.08                              __________________________________________________________________________

In Table 4, ODPA is an abbreviation of 4,4'-oxydiphthalic aciddianhydride; BTDA is an abbreviation of 4,4'-benzophenonetetracarboxylicacid dianhydride; BPDA is an abbreviation of3,3',4,4'-biphenyltetracarboxylic acid dianhydride; APB is anabbreviation of 1,3-bis(3-aminophenoxy)benzene; BAPPF is an abbreviationof 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane; and APPS is anabbreviation of α,ω-bis(3-aminopropyl)polydimethylsiloxane.

The figures in composition column each indicate an equivalent ratio ofeach component in acid or amine components; water absorption refers tothe saturated water absorption of total film when the film was allowedto stand in an environment of 85° C. and 85% (relative humidity) for 168hours (HH-168 treatment); generated gas refers to the amount measured byGC-MS method, of gas generated in total film when the film was heated at250° C. for 15 minutes; and generated water refers to the amountmeasured by Karl Fischer method, of water generated in total film whenthe film was heated at 250° C. for 15 minutes.

Comparative Examples 4-5

Reactions were conducted in the same manner as in Example 10, using therecipes shown in Table 4, to obtain polyimide resins. Film adhesiveswere obtained using the polyimide resins. The results of evaluation forthe film adhesives are shown in Table 4.

In Table 4, PMDA is an abbreviation of 1,2,4,5-benzenetetracarboxylicacid dianhydride; and 4,4'-DDE is an abbreviation of4,4'-diaminodiphenyl ether,

As is clear from the above Examples, the present invention enablesproduction of a film adhesive having high heat resistance and lowhygroscopicity,

Example 15

755 g of dehydrated and purified NMP was placed in a four-necked flaskequipped with an inlet tube for dried nitrogen gas, a cooler, athermometer and a stirrer, and was vigorously stirred for 10 minuteswith nitrogen gas being passed therethrough. Then, thereto were added100.4400 g (0.120 mole) of α,ω-bis(3-aminopropyl)polydimethylsiloxane(APPS), 77.9978 g (0.190 mole) of2,2-bis(4-(4-aminophenoxy)phenyl)propane (BAPP) and 10.8957 g (0.080mole) of 2,5-dimethyl-p-phenylenediamine (DPX). The system was heated to60° C. and stirred until it became uniform. After the system became auniform solution, it was cooled to 5° C. in an ice water bath. Theretowere added, in 15 minutes, 74.4533 g (0.240 mole) of 4,4'-oxydiphthalicacid dianhydride and 47.0752 g (0.160 mole) of3,3',4,4'-biphenyltetracarboxylic acid dianhydride both of powder form.Stirring was conducted for 1 hour, after which stirring was continuedfor 3 hours. During the stirring, the flask was kept at 5° C.Thereafter, 3.7046 g (0.020 mole) of p-phenoxyaniline (PPA) was addedand stirring was continued for 1 hour.

Then, the nitrogen gas inlet tube and the cooler were removed. ADean-Stark tube filled with xylene was fitted to the flask and 188 g oftoluene was added to the system. The system was heated to 175° C. in anoil bath and the water generated was removed out of the system. In 4hours of heating, the generation of water from the system was not seen.After cooling, the reaction mixture was placed in a large amount ofmethanol to precipitate a polyimide resin. The solid was collected byfiltration and vacuum-dried at 80° C. for 12 hours to remove the solventto obtain 284.99 g (yield: 90.6%) of a solid resin. The resin wasmeasured for infrared absorption spectrum by a KBr tablet method, whichgave an absorption at 5.6 μm by cyclic imide bond but no absorption at6.06 μm by amide bond. Thus, it was confirmed that the resin was nearly100% imidized.

The thus-obtained polyimide resin was dissolved in cyclohexanone/toluene(90/10 w/w %) to prepare a polyimide resin varnish having a solidcontent of 25%. This varnish was coated on one side of a polyimide filmUPILEX SGA (trade name) manufactured by Ube Industries, Ltd.! having athickness of 50 μm, by use of a reverse roll coater to obtain anadhesive tape in which the adhesive layer had a thickness of 30 μm. Thedrying temperature was 185° C. (maximum temperature) and the drying timewas 6 minutes. The adhesive tape was hot-pressed onto a 35 μm copperfoil to prepare a test piece. The adhesive tape was contact-bonded onthe treated surface of the copper foil at 250° C. for 2 seconds and,after pressure release, annealing was conducted at 250° C. for 30seconds. The pressure applied onto the adhesion surface was 4 kgf/cm² asa result of calculation from the gauge pressure and the adhesion area.The test piece had a 180° peeling strength of 2.75 kgf/cm and showedexcellent adhesivity. On the rupture surface, the adhesive resin layercaused cohesive failure and no foaming was seen. The results are shownin Table 5.

Example 16

The varnish of Example 15 was coated on a biaxially stretched polyesterfilm DIAFOIL (trade name) manufactured by Mitsubishi Rayon Co., Ltd.!having a thickness of 50 μm. The drying temperature was 185° C. (maximumtemperature) and the drying time was 6 minutes. After drying, thepolyester film was removed by peeling to obtain a single-layer film of32 μm in thickness having no substrate. The peeling was easy and had noparticular problem. The results when the film was bonded to the lustersurface of a copper foil in the same manner as in Example 15, are shownin Table 5.

Examples 17-20

Soluble polyimide resins were obtained in the same manner as in Example15, under the conditions shown in Table 5. The results of evaluation forthese polyimide resins are shown in Table 5. Each of the adhesive tapesshows excellent properties.

                                      TABLE 5                                     __________________________________________________________________________                   Example                                                                              Example                                                                              Example                                                                              Example                                                                              Example                                                                              Example                     Items          15     16     17     18     19     20                          __________________________________________________________________________    Composition                                                                   Acid components                                                               ODPA           60     60     80     80            80                          PMDA                         17.5   17.5                                      BPDA           40     40                   60                                 BTDA                                       40     19                          PA                           5      5             2                           Amine components                                                              APPS           30     30     40     40     25     20                          BAPP           47.5   47.5   30     30     20     40                          APB                                        53     20                          DPX            20     20     30     30            20                          PPA            5      5                    4                                  Acid/amine equivalent ratio r                                                                1.00   1.00   1.00   1.00   1.00   1.00                        Varnish solvent                                                                              Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone               Film drying conditions                                                        Maximum temperature (°C.)                                                             180    180    180    180    180    180                         Time (min)     6      6      6      6      6      6                           Tape constitution                                                             Base           UPILEX Not used                                                                             UPILEX Not used                                                                             Not used                                                                             Not used                    Thickness (μm)                                                                            50/30  30     50/30  30     30     30                          Tape properties                                                               Conditions                                                                              Unit                                                                Water absorption                                                              HH-168 treatment                                                                        %    0.65   0.31   0.58   0.26   0.26   0.34                        Generated gas                                                                 GC-MS method                                                                            ppm  189    210    203    222    204    194                         Generated water                                                               Karl Fischer's method                                                                   %    0.58   0.28   0.61   0.32   0.27   0.31                        Adhesion conditions                                                           Temperature                                                                             °C.                                                                         250    250    250    250    250    250                         Time      Seconds                                                                            2/30   2/30   2/30   2/30   2/30   2/30                        Pressure  kgf/cm.sup.2                                                                       4/0    4/0    4/0    4/0    4/0    4/0                         Adherend       Copper Copper Copper Copper Copper Copper                      Peeling strength                                                              180 ° peeling                                                                    kgf/cm                                                                             2.75   3.14   2.68   2.98   3.05   2.97                        __________________________________________________________________________

In Table 5, ODPA is an abbreviation of 4,4'-oxydiphthalic aciddianhydride; PMDA is an abbreviation of pyromellitic acid anhydride; PAis an abbreviation of phthalic anhydride; APPS is an abbreviation ofα,ω-bis(3-aminopropyl)polydimethylsiloxane; BAPP is an abbreviation of2,2-bis(4-(4-aminophenoxy)phenyl)propane; APB is an abbreviation of1,3-bis(3-aminophenoxy)benzene; DPX is an abbreviation of2,5-dimethyl-p-phenylenediamine; and PPA is an abbreviation ofp-phenoxyaniline.

The figures in composition column each indicate an equivalent ratio ofeach component in acid or amine components; water absorption refers tothe saturated water absorption of total film when the film was allowedto stand in an environment of 85° C. and 85% (relative humidity) for 168hours (HH-168 treatment).

Comparative Examples 6-7

Polyimide resins were obtained in the same manner as in Example 15 underthe conditions shown in Table 6. The results of evolution for thepolyimide resins are shown in Table 6.

                  TABLE 6                                                         ______________________________________                                                           Comparative                                                                              Comparative                                     Items              Example 6  Example 7                                       ______________________________________                                        Composition                                                                   Acid components                                                               ODPA                                                                          PMDA                                                                          BPDA               50         50                                              BTDA               47.5       47.5                                            PA                 5          5                                               Amine components                                                              APPS                                                                          BAPP               100        100                                             APB                                                                           DPX                                                                           PPA                                                                           Acid/amine equivalent ratio r                                                                    1.00       1.00                                            Varnish solvent    NMP        NMP                                             Film drying conditions                                                        Maximum temperature (°C.)                                                                 250        200                                             Time (min)         30         30                                              Tape constitution                                                             Base               UPILEX     Not used                                        Thickness (μm)  50/20      20                                              Tape properties                                                               Conditions  Unit                                                              Water absorption                                                              HH-168 treatment                                                                          %          1.15       0.87                                        Generated gas                                                                 GC-MS method                                                                              ppm        431        542                                         Generated water                                                               Karl Fischer's method                                                                     %          0.78       0.58                                        Adhesion conditions                                                           Temperature °C. 250        250                                         Time        Seconds    2/30       2/30                                        Pressure    kgf/cm.sup.2                                                                             4/0        4/0                                         Adherend               Copper     Copper                                      Peeling strength                                                              180° peeling                                                                       kgf/cm     0.78       (Foamed)                                    ______________________________________                                    

As clear from the above Examples and Comparative Examples, the presentinvention enables production of a polyimide resin soluble in organicsolvents and having high heat resistance and low hygroscopicity.

Examples 23-25

Soluble polyimide resins were obtained in the same manner as in Example15, under the conditions shown in Table 7. The results of evaluation forthese polyimide resins are shown in Table 7. Each of the adhesive tapesshows excellent properties.

                                      TABLE 7                                     __________________________________________________________________________    Items          Example 23                                                                           Example 25                                              __________________________________________________________________________    Composition                                                                   Acid components                                                               ODPA           80     100                                                     BPDA                                                                          BTDA           19                                                             PA             2                                                              Amine components                                                              BAPP           40     70                                                      APB            20     15                                                      DPX            20                                                             APPS           20     15                                                      PPA                                                                           Acid/amine equivalent ratio r                                                                1.00   1.00                                                    Varnish solvent                                                                              Cyclohexanone                                                                        Cyclohexanone                                           Film drying conditions                                                        Maximum temperature (°C.)                                                             180    180                                                     Time (min)     6      6                                                       __________________________________________________________________________    Items          Example 21                                                                           Example 22                                                                           Example 23                                                                           Example 24                                                                           Example 25                         __________________________________________________________________________    Tape constitution                                                             Base           UPILEX Not used                                                                             UPILEX Not used                                                                             Not used                           Thickness (μm)                                                                            50/30  30     50/30  30     30                                 Tape properties                                                               Conditions                                                                              Unit                                                                Water absorption                                                              HH-168 treatment                                                                        %    0.65   0.31   0.59   0.34   0.25                               Generated gas                                                                 GC-MS method                                                                            ppm  189    210    176    194    210                                Generated water                                                               Karl Fischer's method                                                                   %    0.58   0.28   0.47   0.31   0.29                               Adhesion conditions                                                           Temperature                                                                             °C.                                                                         250    250    250    250    250                                Time      Seconds                                                                            2/30   2/30   2/30   2/30   2/30                               Pressure  kgf/cm.sup.2                                                                       4/0    4/0    4/0    4/0    4/0                                Adherend       Copper Copper Copper Copper Copper                             Peeling strength                                                              180° peeling                                                                     kgf/cm                                                                             2.75   3.14   2.83   2.97   2.70                               __________________________________________________________________________

In Table 7, ODPA is an abbreviation of 4,4'-oxydiphthalic aciddianhydride; BPDA is an abbreviation of3,3',4,4'-biphenyltetracarboxylic acid dianhydride; BTDA is anabbreviation of 4,4'-benzophenonetetracarboxylic acid dianhydride; PA isan abbreviation of phthalic anhydride; BAPP is an abbreviation of2,2-bis(4-(4-aminophenoxy)phenyl)propane; APB is an abbreviation of1,3-bis(3-aminophenoxy)benzene; DPX is an abbreviation of2,5-dimethyl-p-phenylenediamine; APPS is an abbreviation ofα,ω-bis(3-aminopropyl)polydimethylsiloxane; and PPA is an abbreviationof p-phenoxyaniline.

The figures in composition column each indicate an equivalent ratio ofeach component in acid or amine components; water absorption refers tothe saturated water absorption when the film was allowed to stand in anenvironment of 85° C. and 85% (relative humidity) for 168 hours (HH-168treatment); generated gas refers to the amount measured by GC-MS method,of gas generated when the film was heated at 250° C. for 15 minutes; andgenerated water refers to the amount measured by Karl Fischer method, ofwater generated when the film was heated at 250° C. for 15 minutes. S insolubility column indicates "soluble in the relevant solvent".

Example 26

688 g of dehydrated and purified NMP was placed in a four-necked flaskequipped with an inlet tube for dried nitrogen gas, a cooler, athermometer and a stirrer, and was vigorously stirred for 10 minuteswith nitrogen gas being passed therethrough. Then, thereto were added65.6823 g (0.160 mole) of 2,2-bis(4-(4-aminophenoxy)phenyl)propane(BAPP), 23.3869 g (0.08 mole) of 1,3-bis(3-aminophenoxy)benzene (APB),10.8957 g (0.080 mole) of dimethylphenylenediamine (DPX) and 66.9600 g(average molecular weight: 837, 0.080 mole) ofα,ω-bis(3-aminopropyl)polydimethylsiloxane (APPS). The system was heatedto 60° C. and stirred until it became uniform. After the system became auniform solution, 2.3699 g (0.016 mole) of phthalic anhydride was added.The mixture was stirred for 1 hour. Then, the system was cooled to 5° C.in an ice water bath. Thereto were added, in 15 minutes, 91.7966 g(0.312 mole) of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and25.7784 g (0.08 mole) of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride both of powder form. Then, stirring was continued for 3hours.

Then, the nitrogen gas inlet tube and the cooler were removed. ADean-Stark tube filled with xylene was fitted to the flask and 172 g oftoluene was added to the system. The system was heated to 175° C. in anoil bath and the water generated was removed out of the system. In 4hours of heating, the generation of water from the system was not seen.After cooling, the reaction mixture was placed in a large amount ofmethanol to precipitate a polyimide resin. The solid was collected byfiltration and vacuum-dried at 80° C. for 12 hours to remove the solventto obtain 257.32 g (yield: 89.7%) of a solid resin. The resin wasmeasured for infrared absorption spectrum by a KBr tablet method, whichgave an absorption at 5.6 μm by cyclic imide bond but no absorption at6.06 μm by amide bond. Thus, it was confirmed that the resin was nearly100% imidized. Incidentally, the molar ratios of the acid components andamine components were a/(a+b+0.5f)=0.78, b/(a+b+0.5f)=0.2 ande/(c+d+e)=0.2, respectively.

The thus-obtained polyimide resin was dissolved in cyclohexanone/toluene(90/10 w/w %) to prepare a polyimide resin varnish having a solidcontent of 25%. This varnish was coated on one side of a polyimide filmUPILEX SGA (trade name) manufactured by Ube Industries, Ltd.! having athickness of 50 μm, by use of a reverse roll coater to obtain anadhesive tape in which the adhesive layer had a thickness of 30 μm. Thedrying temperature was 185° C. (maximum temperature) and the drying timewas 6 minutes. The adhesive tape was hot-pressed onto a 35 μm copperfoil to prepare a test piece. The adhesive tape was contact-bonded onthe treated surface of the copper foil at 250° C. for 2 seconds and,after pressure release, annealing was conducted at 250° C. for 30seconds. The pressure applied onto the adhesion surface was 4 kgf/cm² asa result of calculation from the gauge pressure and the adhesion area.The test piece had a 180° peeling strength of 3.12 kgf/cm and showedexcellent adhesivity. On the rupture surface, the adhesive resin layercaused cohesive failure and no foaming was seen. The results are shownin Table 8.

Example 27

The varnish of Example 26 was coated on a biaxially stretched polyesterfilm DIAFOIL (trade name) manufactured by Mitsubishi Rayon Co., Ltd.!having a thickness of 50 μm. The drying temperature was 185° C. (maximumtemperature) and the drying time was 6 minutes. After drying, thepolyester film was removed by peeling to obtain a single-layer film of30 μm in thickness having no substrate. The peeling was easy and had noparticular problem. The results when the film was bonded to the lustersurface of a copper foil in the same manner as in Example 26, are shownin Table 8.

Examples 28-30

Soluble polyimide resins were obtained in the same manner as in Example26, under the conditions shown in Table 8. The results of evaluation forthese polyimide resins are shown in Table 8. Each of the adhesive tapesshows excellent properties.

                                      TABLE 8                                     __________________________________________________________________________    Items          Example 26                                                                           Example 27                                                                           Example 28                                                                           Example 29                                                                           Example 30                         __________________________________________________________________________    Composition                                                                   Acid components                                                               BPDA           78     78     50     50     60                                 BTDA           20     20     50     50     40                                 PA             4      4                                                       Amine components                                                              BAPP           40     40     39     39     20                                 APB            20     20                   55                                 DPX            20     20     30     30                                        APPS           20     20     30     30     25                                 PPA                          2      2                                         Acid/amine equivalent ratio r                                                                1.00   1.00   1.00   1.00   1.00                               Varnish solvent                                                                              Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                                                                        Cyclohexanone                      Film drying conditions                                                        Maximum temperature (°C.)                                                             180    180    180    180    180                                Time (min)     6      6      6      6      6                                  Tape consitution                                                              Base           UPILEX Not used                                                                             UPILEX Not used                                                                             Not used                           Thickness (μm)                                                                            50/30  30     50/30  30     30                                 Tape properties                                                               Conditions                                                                              Unit                                                                Water absorption                                                              HH-168 treatment                                                                        %    0.60   0.28   0.58   0.28   0.24                               Generated gas                                                                 GC-MS method                                                                            ppm  225    240    202    238    212                                Generated water                                                               Karl Fischer's method                                                                   %    0.58   0.23   0.43   0.25   0.29                               Adhesion conditions                                                           Temperature                                                                             °C.                                                                         250    250    250    250    250                                Time      Seconds                                                                            2/30   2/30   2/30   2/30   2/30                               Pressure  kgf/cm.sup.2                                                                       4/0    4/0    4/0    4/0    4/0                                Adherend       Copper Copper Copper Copper Copper                             Peeling strength                                                              180° peeling                                                                     kgf/cm                                                                             3.12   3.34   2.75   2.78   3.18                               __________________________________________________________________________

In Table 8, BPDA is an abbreviation of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride; BTDA is an abbreviation of4,4'-benzophenonetetracarboxylic acid dianhydride; PA is an abbreviationof phthalic anhydride; BAPP is an abbreviation of2,2-bis(4-(4-aminophenoxy)phenyl)propane; APB is an abbreviation of1,3-bis(3-aminophenoxy)benzene; DPX is an abbreviation of2,5-dimethyl-p-phenylenediamine; APPS is an abbreviation ofα,ω-bis(3-aminopropyl)polydimethylsiloxane; and PPA is an abbreviationof p-phenoxyaniline.

The figures in composition column each indicate an equivalent ratio ofeach component in acid or amine components; water absorption refers tothe saturated water absorption of total film when the film was allowedto stand in an environment of 85° C. and 85% (relative humidity) for 168hours (HH-168 treatment); generated gas refers to the amount measured byGC-MS method, of gas generated from total film when the film was heatedat 250° C. for 15 minutes; and generated water refers to the amountmeasured by Karl Fischer method, of water generated from total film whenthe film was heated at 250° C. for 15 minutes.

INDUSTRIAL APPLICABILITY

The present invention can provide a film adhesive of high reliabilityhaving both heat resistance and adhesion workability. The present filmadhesive provides an advantage particularly when copper, which is easilyoxidized, is used as a lead frame, because the present film adhesive canbe applied at low temperatures in a short time without incurring theoxidation of copper surface. Further, since the present film adhesive issoluble in low-boiling solvents, the residual solvent content in thefilm can be controlled at a very low level by using mild dryingconditions as compared with the drying conditions used for conventionalpolyimides. Furthermore, since the present film adhesive is alreadyimidized, no high-temperature step is required for imidization and nowater is generated, during the application of the adhesive. Thus, thepresent film adhesive has features such as low water absorption, lowimpurities content, generation of very small amount of gas duringheating, and the like; therefore, it has a very high industrial value asan electronics material in which high reliability and heat resistanceare required, particularly as a material for mounting of semiconductors.

We claim:
 1. A film adhesive comprising, as the main constituent, apolyimide resin having a glass transition temperature of 350° C. orlower and soluble in organic solvents, which polyimide resin is obtainedby reacting at least one of the following acid components (A) and (B)(A)4,4'-oxydiphthalic acid dianhydride (B)3,3',4,4'-biphenyltetracarboxylic acid dianhydride and/or3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith the followingamine components (C) and (D) (C) a siloxane compound represented by thefollowing general formula (1) and/or2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR7## wherein R₁ and R₂ areeach a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅ and R₆are each a mono-valent aliphatic or aromatic group; and k is an integerof 1-20, (D) 1,3-bis(3-aminophenoxy)benzene and/ordimethylphenylene-diamineto give rise to ring closure of imide.
 2. Afilm adhesive according to claim 1, wherein the polyimide resin iscomposed by using the acid component (A), i.e. 4,4'-oxydiphthalic aciddianhydride in an amount of 60 mole % or more based on the total amountof the acid components.
 3. A film adhesive according to claim 1, whereinthe polyimide resin is composed by using, as the acid component (B), pmoles of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q molesof 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride in proportionssatisfying 0.5≦p/(p+q)≦0.9.
 4. A film adhesive according to claim 1,wherein the polyimide resin is composed by using, as the amine component(C), a siloxane compound represented by general formula (1) in an amountof 5-60 mole % based on the total amount of the amine components.
 5. Afilm adhesive according to claim 1, wherein the polyimide resin iscomposed by using, as the amine component (D),1,3-bis(3-aminophenoxy)benzene in an amount of 10-90 mole % based on thetotal amount of the amine components.
 6. A film adhesive according toclaim 1, wherein the polyimide resin is composed by using, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine in proportions satisfying a/(a+b)≧0.6,0.6>b/(a+b)≧0, 0.1≦c/(c+d+e)≦0.6, 0.6≦(c+d)/(c+d+e), 0≦e/(c+d+e)<0.6 and0.950<(a+b)/(c+d+e)<1.02.
 7. A film adhesive according to claim 1,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of anothertetracarboxylic acid dianhydride and, as the amine components, c molesof α,ω-bis(3-aminopropyl)polydimethylsiloxane, d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine and emoles of another diamine, and wherein the polyimide resin is capped, atthe molecular ends, with f moles of an acid anhydride represented bygeneral formula (2) or g moles of an aromatic amine represented bygeneral formula (3), and wherein the molar ratios of a, b, c, d, e, fand g satisfy 0.6≦a/(a+b+0.5f), 0≦b/(a+b+0.5f)<0.6,0.1≦c/(c+d+e+0.5g)≦0.6, 0≦e/(c+d+e+0.5g)<0.6, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+d+e+0.5g)≦0.05 and either of f and g is
 0. 8. A film adhesiveaccording to claim 1, wherein the polyimide resin is composed by using,as the acid components, p moles of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylicacid dianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene in proportions satisfying 0.5≦p/(p+q)≦0.9and 0.1≦d/(c'+d)≦0.9.
 9. A film adhesive according to claim 1, whereinthe polyimide resin is composed of, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c' moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and dmoles of 1,3-bis(3-aminophenoxy)benzene, and wherein the polyimide resinis capped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of p,q, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9, 0.1≦d/(c'+d+0.5g)≦0.9,0.01≦f/(p+q+0.5f)≦0.05 and 0.01≦/(c'+d+0.5g)≦0.05 and either of f and gis
 0. 10. A film adhesive according to claim 1, wherein the polyimideresin is composed by using, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of p, q, c, c' and d satisfy 0.5≦p/(p+q)≦0.9,0.1≦q/(p+q)≦0.5 and 0.05≦c/(c+c'+d)≦0.5.
 11. A film adhesive accordingto claim 1, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of p, q, c, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9,0.1≦q/(p+q+0.5f)≦0.5, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(p+q+0.5f)≦0.05and 0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 12. A filmadhesive according to claim 1, wherein the polyimide resin is composedof, as the acid components, a moles of 4,4'-oxydiphthalic aciddianhydride and b moles of one or two tetracarboxylic acid dianhydridesselected from the group consisting of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of a, b, c, c' and d satisfy a/(a+b)≧0.6, b/(a+b)≦0.4and 0.05≦c/(c+c'+d)≦0.5.
 13. A film adhesive according to claim 1,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of one or twotetracarboxylic acid dianhydrides selected from the group consisting of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of a, b, c, c', d, f and g satisfy a/(a+b+0.5f)≧0.6,b/(a+b+0.5f)≦0.4, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 14. A filmadhesive comprising a heat-resistant film base and a film adhesive ofclaim 1, applied on one side or both sides of the film base.
 15. A filmadhesive according to claim 14, wherein the heat-resistant film base isa polyimide film having a glass transition temperature of 350° C. orhigher.
 16. A process for producing a film adhesive, which comprisescasting, on one side or both sides of a substrate, an organic solventsolution of a polyimide resin having a glass transition temperature of350° C. or lower and soluble in organic solvents, said polyimide resinbeing obtained by reacting at least one of the following acid components(A) and (B)(A) 4,4'-oxydiphthalic acid dianhydride (B)3,3',4,4'-biphenyltetracarboxylic acid dianhydride and/or3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith the followingamine components (C) and (D) (C) a siloxane compound represented by thefollowing general formula (1) and/or2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR8## wherein R₁ and R₂ areeach a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅ and R₆are each a mono-valent aliphatic or aromatic group; and k is an integerof 1-20, (D) 1,3-bis(3-aminophenoxy)benzene and/ordimethylphenylene-diamineto give rise to ring closure of imide.
 17. Aprocess for producing a film adhesive according to claim 16, wherein thesubstrate is a polyimide film having a glass transition temperature of350° C. or higher.
 18. A process for producing a film adhesive, whichcomprisescasting, on one side or both sides of a substrate, an organicsolvent solution of a polyimide resin having a glass transitiontemperature of 350° C. or lower and soluble in organic solvents, saidpolyimide resin being obtained by reacting at least one of the followingacid components (A) and (B) (A) 4,4'-oxydiphthalic acid dianhydride (B)3,3',4,4'-biphenyltetracarboxylic acid dianhydride and/or3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith the followingamine components (C) (D) (C) a siloxane compound represented by thefollowing general formula (1) and/or2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR9## wherein R₁ and R₂ areeach a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅ and R₆are each a mono-valent aliphatic or aromatic group; and k is an integerof 1-20, (D) 1,3-bis(3-aminophenoxy)benzene and/ordimethylphenylene-diamineto give rise to ring closure of imide, andpeeling the substrate after casting and drying.
 19. A film adhesivecomprising, as the main constituent, a polyimide resin having a glasstransition temperature of 350° C. or lower and soluble in organicsolvents, which polyimide resin is obtained by reacting at least one ofthe following acid components (A) and (B)(A) 4,4'-oxydiphthalic aciddianhydride (B) 3,3',4,4'-biphenyltetracarboxylic acid dianhydrideand/or 3,3,4-benzophenonetetracarboxylic acid dianhydridewith thefollowing amine components (C) and (D) (C) a siloxane compoundrepresented by the following general formula (1) ##STR10## wherein R₁and R₂ are each a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄,R₅ and R₆ are each a mono-valent aliphatic or aromatic group; and k isan integer of 1-20, (D) 2,2-bis(4-(4-amino-phenoxy)phenyl)propane and/or1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylene-diamine to giverise to ring closure of imide.
 20. A process for producing a filmadhesive, which comprises casting, on one side or both sides of asubstrate, an organic solvent solution of a polyimide resin having aglass transition temperature of 350° C. or lower and soluble in organicsolvents, said polyimide resin being obtained by reacting at least oneof the following acid components (A) and (B)(A) 4,4'-oxydiphthalic aciddianhydride (B) 3,3',4,4'-biphenyltetracarboxylic acid dianhydrideand/or 3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith thefollowing amine components (C) and (D) (C) a siloxane compoundrepresented by the following general formula (1) ##STR11## wherein R₁and R₂ are each a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄,R₅ and R₆ are each a mono-valent aliphatic or aromatic group; and k isan integer of 1-20, (D) 2,2-bis(4-(4-amino-phenoxy)phenyl)propane and/or1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylene-diamine to giverise to ring closure of imide.
 21. A film adhesive according to claim19, wherein polyimide resin is capped, at the molecular ends, with anacid anhydride represented by the following general formula (2) or anaromatic amine represented by the following general formula (3):##STR12## (X is at least one group selected from ##STR13## wherein Y isat least one group selected from hydrogen, methyl, ethyl, propyl, butyl,phenyl, methoxy, ethoxy, propoxy, butoxy and phenoxy groups.
 22. Aprocess for producing a film adhesive according to claim 24, wherein thepolyimide resin is capped, at the molecular ends, with an acid anhydriderepresented by the following general formula (2) or an aromatic aminerepresented by the following general formula (3): ##STR14## (X is atleast one group selected from ##STR15## wherein Y is at least one groupselected from hydrogen, methyl, ethyl, propyl, butyl, phenyl, methoxy,ethoxy, propoxy, butoxy and phenoxy groups.
 23. A film adhesiveaccording to claim 19, wherein the polyimide resin is composed by usingthe acid component (A) 4,4'-oxydiphthalic acid dianhydride in an amountof 60 mole % or more based on the total amount of the acid components.24. A film adhesive according to claim 19, wherein the polyimide resinis composed by using, as the acid component (B), p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride in proportionssatisfying 0.5≦p/(p+q)≦0.9.
 25. A film adhesive according to claim 19,wherein the polyimide resin is composed by using, as the amine component(C), a siloxane compound represented by general formula (1) in an amountof 5-60 mole % based on the total amount of the amine components.
 26. Afilm adhesive according to claim 19, wherein the polyimide resin iscomposed by using, as the amine component (D),1,3-bis(3-aminophenoxy)benzene in an amount of 10-90 mole % based on thetotal amount of the amine components.
 27. A film adhesive according toclaim 19, wherein the polyimide resin is composed by using, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine in proportions satisfying a/(a+b)≧0.6,0.6>b/(a+b)≧0, 0.1≦c/(c+d+e)≦0.6, 0.6≦(c+d)/(c+d+e), 0≦e/(c+d+e)<0.6 and0.950<(a+b)/(c+d+e)<1.02.
 28. A film adhesive according to claim 19,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of anothertetracarboxylic acid dianhydride and, as the amine components, c molesof α,ω-bis(3-aminopropyl)polydimethylsiloxane, d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine and emoles of another diamine, and wherein the polyimide resin is capped, atthe molecular ends, with f moles of an acid anhydride represented bygeneral formula (2) or g moles of an aromatic amine represented bygeneral formula (3), and wherein the molar ratios of a, b, c, d, e, fand g satisfy 0.6≦a/(a+b+0.5f), 0≦b/(a+b+0.5f)<0.6,0.1≦c/(c+d+e+0.5g)≦0.6, 0≦e/(c+d+e+0.5g)<0.6, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+d+e+0.5g)≦0.05 and either of f and g is
 0. 29. A film adhesiveaccording to claim 19, wherein the polyimide resin is composed by using,as the acid components, p moles of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylicacid dianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene in proportions satisfying 0.5≦p/(p+q)≦0.9and 0.1≦d/(c'+d)≦0.9.
 30. A film adhesive according to claim 19, whereinthe polyimide resin is composed of, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c' moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and dmoles of 1,3-bis(3-aminophenoxy)benzene, and wherein the polyimide resinis capped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of p,q, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9, 0.1≦d/(c'+d+0.5g)≦0.9,0.01≦f/(p+q+0.5f)≦0.05 and 0.01≦g/(c'+d+0.5g)≦0.05 and either of f and gis
 0. 31. A film adhesive according to claim 19, wherein the polyimideresin is composed by using, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of p, q, c, c' and d satisfy 0.5≦p/(p+q)≦0.9,0.1≦q/(p+q)≦0.5 and 0.05≦c/(c+c'+d)≦0.5.
 32. A film adhesive accordingto claim 19, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of p, q, c, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9,0.1≦q/(p+q+0.5f)≦0.5, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(p+q+0.5f)≦0.05and 0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 33. A filmadhesive according to claim 19, wherein the polyimide resin is composedof, as the acid components, a moles of 4,4'-oxydiphthalic aciddianhydride and b moles of one or two tetracarboxylic acid dianhydridesselected from the group consisting of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of a, b, c, c' and d satisfy a/(a+b)≧0.6, b/(a+b)≦0.4and 0.05≦c/(c+c'+d)≦0.5.
 34. A film adhesive according to claim 19,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of one or twotetracarboxylic acid dianhydrides selected from the group consisting of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of a, b, c, c', d, f and g satisfy a/(a+b+0.5f)≧0.6,b/(a+b+0.5f)≦0.4, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 35. A filmadhesive comprising a heat-resistant film base and a film adhesiveaccording to claim 19, applied on one side or both sides of the filmbase.
 36. A film adhesive according to claim 35, wherein theheat-resistant film base is a polyimide film having a glass transitiontemperature of 350° C. or higher.
 37. A process for producing a filmadhesive according to claim 20, wherein the substrate is a polyimidefilm having a glass transition temperature of 350° C. or higher.
 38. Aprocess for producing a film adhesive according to claim 20, whichcomprises peeling the substrate after casting and drying.
 39. A processaccording to claim 38 wherein the substrate is a biaxially stretchedpolyester film.
 40. A process for producing a film adhesive according toclaim 20, which comprises casting said polyimide resin solution on asubstrate by use of an organic solvent having a boiling point of 180° C.or lower, drying the cast polyimide resin solution and peeling the driedpolyimide resin from the substrate.
 41. A film adhesive according toclaim 21, wherein the polyimide resin is composed by using the acidcomponent (A), 4,4'-oxydiphthalic acid dianhydride in an amount of 60mole % or more based on the total amount of the acid components.
 42. Afilm adhesive according to claim 21, wherein the polyimide resin iscomposed by using, as the acid component (B), p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride in proportionssatisfying 0.5≦p/(p+q)≦0.9.
 43. A film adhesive according to claim 21,wherein the polyimide resin is composed by using, as the amine component(C), a siloxane compound represented by general formula (1) in an amountof 5-60 mole % based on the total amount of the amine components.
 44. Afilm adhesive according to claim 21, wherein the polyimide resin iscomposed by using, as the amine component (D),1,3-bis(3-aminophenoxy)benzene in an amount of 10-90mole % based on thetotal amount of the amine components.
 45. A film adhesive according toclaim 21, wherein the polyimide resin is composed by using, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine in proportions satisfying a/(a+b)≧0.6,0.6>b/(a+b)≧0, 0.1≦c/(c+d+e)≦0.6, 0.6≦(c+d)/(c+d+e), 0≦e/(c+d+e)<0.6 and0.950<(a+b)/(c+d+e)<1.02.
 46. A film adhesive according to claim 21,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of anothertetracarboxylic acid dianhydride and, as the amine components, c molesof α,ω-bis(3-aminopropyl)polydimethylsiloxane, d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine and emoles of another diamine, and wherein the polyimide resin is capped, atthe molecular ends, with f moles of an acid anhydride represented bygeneral formula (2) or g moles of an aromatic amine represented bygeneral formula (3), and wherein the molar ratios of a, b, c, d, e, fand g satisfy 0.6≦a/(a+b+0.5f), 0≦b/(a+b+0.5g)<0.6,0.1≦c/(c+d+e+0.5g)≦0.6, 0≦e/(c+d+e+0.5g)<0.1, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+d+e+0.5g)≦0.05 and either of f and g is
 0. 47. A film adhesiveaccording to claim 21, wherein the polyimide resin is composed by using,as the acid components, p moles of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and q moles of 3',3',4,4'-benzophenonetetracarboxylicacid dianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene in proportions satisfying 0.5≦p/(p+q)≦0.9and 0.1≦d/(c'+d)≦0.9.
 48. A film adhesive according to claim 21, whereinthe polyimide resin is composed of, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c' moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and dmoles of 1,3-bis(3-aminophenoxy)benzene, and wherein the polyimide resinis capped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of p,q, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9, 0.1≦d/(c'+d+0.5g)≦0.9,0.01≦f/(p+q+0.5f)≦0.05 and 0.01≦g/(c'+d+0.5g)≦0.05 and either of f and gis
 0. 49. A film adhesive according to claim 21, wherein the polyimideresin is composed by using, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of p, q, c, c' and d satisfy 0.5≦p/(p+q)≦0.9,0.1≦q/(p+q)≦0.5 and 0.05≦c/(c+c'+d)≦0.5.
 50. A film adhesive accordingto claim 21, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of p, q, c, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9,0.1≦q/(p+q+0.5f)≦0.5, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(p+q+0.5f)≦0.05and 0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 51. A filmadhesive according to claim 21, wherein the polyimide resin is composedof, as the acid components, a moles of 4,4'-oxydiphthalic aciddianhydride and b moles of one or two tetracarboxylic acid dianhydridesselected from the group consisting of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of a, b, c, c' and d satisfy a/(a+b)≧0.6, b/(a+b)≦0.4and 0.05≦c/(c+c'+d)≦0.5.
 52. A film adhesive according to claim 21,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of one or twotetracarboxylic acid dianhydrides selected from the group consisting of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of a, b, c, c', d, f and g satisfy a/(a+b+0.5f)≧0.6,b/(a+b+0.5f)≦0.4, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 53. A filmadhesive comprising a heat-resistant base and a film adhesive accordingto claim 21, applied on one side or both sides of the film base.
 54. Afilm adhesive according to claim 53, wherein the heat-resistant filmbase is a polyimide film having a glass transition temperature of 350°C. or higher.
 55. A process for producing a film adhesive according toclaim 22, wherein the substrate is a polyimide film having a glasstransition temperature of 350° C. or higher.
 56. A process for producinga film adhesive according to claim 22, which comprises peeling thesubstrate after casting and drying.
 57. A process according to claim 56,wherein the substrate is a biaxially stretched polyester film.
 58. Aprocess for producing a film adhesive according to claim 22, whichcomprises casting said polyimide resin solution on a substrate by use ofan organic solvent having a boiling point of 180° C. or lower, dryingthe cast polyimide resin solution and peeling the dried polyimide resinfrom the substrate.
 59. A film adhesive comprising as the mainconstituent, a polyimide resin having a glass transition temperature of350° C. or lower and soluble in organic solvents, which polyimide resinis obtained by reacting at least one of the following acid components(A) and (B)(A) 4,4'-oxydiphthalic acid dianhydride (B)3,3',4,4'-biphenyltetracarboxylic acid dianhydride and/or3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith at least oneof the following amine components (C) and (D) (C) a siloxane compoundrepresented by the following general formula (1) and/or2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR16## wherein R₁ and R₂are each a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅ andR₆ are each a mono-valent aliphatic or aromatic group; and k is aninteger of 1-20, (D) bis(aminophenoxy)benzene and/ordimethylphenylene-diamineto give rise to ring closure of imide, andwherein the polyimide resin is capped, at the molecular ends,with anacid anhydride represented by the following general formula (2) or anaromatic amine represented by the following general formula (3):##STR17## (X is at least one group selected from ##STR18## wherein Y isat least one group selected from hydrogen, methyl, ethyl, propyl, butyl,phenyl, methoxy, ethoxy, propoxy, butoxy and phenoxy groups.
 60. A filmadhesive according to claim 59, wherein the polyimide resin is composedby using the acid component (A) 4,4'-oxydiphthalic acid dianhydride inan amount of 60 mole % or more based on the total amount of the acidcomponents.
 61. A film adhesive according to claim 59, wherein thepolyimide resin is composed by using, as the acid component (B), p molesof 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride in proportionssatisfying 0.5≦p/(p+q)≦0.9.
 62. A film adhesive according to claim 59,wherein the polyimide resin is composed by using, as the amine component(C), a siloxane compound represented by general formula (1) in an amountof 5-60 mole % based on the total amount of the amine components.
 63. Afilm adhesive according to claim 59, wherein the polyimide resin iscomposed by using, as the amine component (D),1,3-bis(3-aminophenoxy)benzene in an amount of 10-90 mole % based on thetotal amount of the amine components.
 64. A film adhesive according toclaim 59, wherein the polyimide resin is composed by using, as the acidcomponents, a moles of 4,4'-oxydiphthalic acid dianhydride and b molesof another tetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, dmoles of 1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamineand e moles of another diamine in proportions satisfying a/(a+b)≧0.6,0.6>b/(a+b)≧0, 0.1≦c/(c+d+e)≦0.6, 0.6≦(c+d)/(c+d+e), 0≦e/(c+d+e)<0.6 and0.950<(a+b)/(c+d+e)<1.02.
 65. A film adhesive according to claim 59,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of anothertetracarboxylic acid dianhydride and, as the amine components, c molesof α,ω-bis(3-aminopropyl)polydimethylsiloxane, d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine and emoles of another diamine, and wherein the polyimide resin is capped, atthe molecular ends, with f moles of an acid anhydride represented bygeneral formula (2) or g moles of an aromatic amine represented bygeneral formula (3), and wherein the molar ratios of a, b, c, d, e, fand g satisfy 0.6≦a/(a+b+0.5f), 0≦b/(a+b+0.5f)<0.6,0.1≦c/(c+d+e+0.5g)≦0.6, 0≦e/(c+d+e+0.5g)<0.6, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+d+e+0.5g)≦0.05 and either of f and g is
 0. 66. A film adhesiveaccording to claim 59, wherein the polyimide resin is composed by using,as the acid components, p moles of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylicacid dianhydride and, as the amine components, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene in proportions satisfying 0.5≦p/(p+q)≦0.9and 0.1≦d/(c'+d)≦0.9.
 67. A film adhesive according to claim 59, whereinthe polyimide resin is composed of, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c' moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and dmoles of 1,3-bis(3-aminophenoxy)benzene, and wherein the polyimide resinis capped, at the molecular ends, with f moles of an acid anhydriderepresented by general formula (2) or g moles of an aromatic aminerepresented by general formula (3), and wherein the molar ratios of p,q, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9, 0.1≦d/(c'+d+0.5g)≦0.9,0.01≦f/(p+q+0.5f)≦0.05 and 0.01≦g/(c'+d+0.5g)≦0.05 and either of f and gis
 0. 68. A film adhesive according to claim 59, wherein the polyimideresin is composed by using, as the acid components, p moles of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and q moles of3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of p, q, c, c' and d satisfy 0.5≦p/(p+q)≦0.9,0.1≦q/(p+q)≦0.5 and 0.05≦c/(c+c'+d)≦0.5.
 69. A film adhesive accordingto claim 59, wherein the polyimide resin is composed of, as the acidcomponents, p moles of 3,3',4,4'-biphenyltetracarboxylic aciddianhydride and q moles of 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of p, q, c, c', d, f and g satisfy 0.5≦p/(p+q+0.5f)≦0.9,0.1≦q/(p+q+0.5f)≦0.5, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(p+q+0.5f)≦0.05and 0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 70. A filmadhesive according to claim 59, wherein the polyimide resin is composedof, as the acid components, a moles of 4,4'-oxydiphthalic aciddianhydride and b moles of one or two tetracarboxylic acid dianhydridesselected from the group consisting of 3,3',4,4'-biphenyltetracarboxylicacid dianhydride and 3,3',4,4'-benzophenonetetracarboxylic aciddianhydride and, as the amine components, c moles ofα,ω-bis(3-aminopropyl)polydimethylsiloxane, c' moles of2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine so thatthe molar ratios of a, b, c, c' and d satisfy a/(a+b)≧0.6, b/(a+b)≦0.4and 0.05≦c/(c+c'+d)≦0.5.
 71. A film adhesive according to claim 59,wherein the polyimide resin is composed of, as the acid components, amoles of 4,4'-oxydiphthalic acid dianhydride and b moles of one or twotetracarboxylic acid dianhydrides selected from the group consisting of3,3',4,4'-biphenyltetracarboxylic acid dianhydride and3,3',4,4'-benzophenonetetracarboxylic acid dianhydride and, as the aminecomponents, c moles of α,ω-bis(3-aminopropyl)polydimethylsiloxane, c'moles of 2,2-bis(4-(4-aminophenoxy)phenyl)propane and d moles of1,3-bis(3-aminophenoxy)benzene and/or dimethylphenylenediamine, andwherein the polyimide resin is capped, at the molecular ends, with fmoles of an acid anhydride represented by general formula (2) or g molesof an aromatic amine represented by general formula (3), and wherein themolar ratios of a, b, c, c', d, f and g satisfy a/(a+b+0.5f)≧0.6,b/(a+b+0.5f)≦0.4, 0.05≦c/(c+c'+d+0.5g)≦0.5, 0.01≦f/(a+b+0.5f)≦0.05 and0.01≦g/(c+c'+d+0.5g)≦0.05 and either of f and g is
 0. 72. A filmadhesive comprising a heat-resistant film base and a film adhesiveaccording to claim 59, applied on one side or both sides of the filmbase.
 73. A film adhesive according to claim 72, wherein theheat-resistant film base is a polyimide film having a glass transitiontemperature of 350° C. or higher.
 74. A process for producing a filmadhesive, which comprises casting, on one side or both sides of asubstrate, an organic solvent solution of a polyimide resin having aglass transition temperature of 350° C. or lower and soluble in organicsolvents, said polyimide resin being obtained by reacting at least oneof the following acid components (A) and (B)(A) 4,4'-oxydiphthalic aciddianhydride (B) 3,3',4,4'-biphenyltetracarboxylic acid dianhydrideand/or 3,3',4,4'-benzophenonetetracarboxylic acid dianhydridewith atleast one of the following amine components (C) and (D) (C) a siloxanecompound represented by the following general formula (1) and/or2,2-bis(4-(4-amino-phenoxy)phenyl)propane ##STR19## wherein R₁ and R₂are each a bivalent aliphatic (C₁₋₄) or aromatic group; R₃, R₄, R₅ andR₆ are each a mono-valent aliphatic or aromatic group; and k is aninteger of 1-20, (D) bis(aminophenoxy)benzene and/ordimethylphenylene-diamineto give rise to ring closure of imide, andwherein the polyimide resin is capped, at the molecular ends, with anacid anhydride represented by the following general formula (2) or anaromatic amine represented by the following general formula (3):##STR20## (X is at least one group selected from ##STR21## wherein Y isat least one group selected from hydrogen atom and methyl, ethyl,propyl, butyl, phenyl, methoxy, ethoxy, propoxy, butoxy and phenoxygroups.
 75. A process for producing a film adhesive according to claim74, wherein the substrate is a polyimide film having a glass transitiontemperature of 350° C. or higher.
 76. A process for producing a filmadhesive according to claim 74, which comprises peeling the substrateafter casting and drying.
 77. A process according to claim 76, whereinthe substrate is a biaxially stretched polyester film.
 78. A process forproducing a film adhesive according to claim 74, which comprises castingsaid polyimide resin solution on a substrate by use of an organicsolvent having a boiling point of 180° C. or lower, drying the castpolyimide resin solution and peeling the dried polyimide resin from thesubstrate.
 79. A process according to claim 18, wherein the substrate isa biaxially stretched polyester film.
 80. A process for producing a filmadhesive according to claim 18, wherein said organic solvent solution ofsaid polyamide is in an organic solvent having a boiling point of 180°C. or lower.